Thermal stability and hardness of ReB2 type hexagonal OsB2 with the addition of W. Issue 14 (1st October 2018)

• Record Type: Journal Article
• Authors: Zheng, Xin; Long, Ying; Zou, Canhui; Lin, Hua-Tay; Zhang, Fenglin; An, Linan
• Is Part Of: Ceramics international. Volume 44:Issue 14(2018)
• Page Start: 16302
• Page End: 16306
• Publication Date: 2018-10-01
• Subjects: Os1-xWxB2 solid solution -- Phase composition -- Microstructure -- Microhardness; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2018.06.029
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: This work attempts to understand the effect of W addition on microstructure, thermal stability, and hardness of ReB2 type hexagonal osmium diboride ( h- OsB2 ). h- OsB2 samples with W atomic concentration of (Os+W) from 0% to 30% were synthesized by mechanochemical method combines with pressure-less sintering. The XRD patterns of the as-synthesized powders indicate the formation of Os1-x Wx B2 (x = 0, 0.1, 0.2 and 0.3) solid solution, which has a ReB2 -type hexagonal structure. After being high temperature sintered, part of the h -OsB2 phase of the pure OsB2 transformed to orthorhombic ( o ) phase, while the h -OsB2 phase was maintained with the addition of W, which suggests that the thermal stability of the sample was remarkably improved. A macroscopically homogeneous structure with some pores can be found from all groups of the as-sintered Os1-x Wx B2 (x = 0, 0.1, 0.2, 0.3) samples, with some B-rich areas distributed in the W doped samples. The lattice parameters of the Os1-x Wx B2 (x = 0, 0.1, 0.2 and 0.3) solid solutions linearly decreased with the increase of the W concentration. The micro-hardness of the OsB2 sintered samples is 25 ± 2 GPa under an applied load of 0.49 N, which increased to 34 ± 2 GPa, 38 ± 2 and 37 ± 2 GPa, respectively when the W concentration increased from 10, 20 and 30 at%. The increased hardness of the h -OsB2 can be mainly attributed to the improvement of thermal stability with the addition of W.